Lamprophyres typically appear in hydrothermal gold deposits.The relationship between lamprophyres and gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers gold mi...Lamprophyres typically appear in hydrothermal gold deposits.The relationship between lamprophyres and gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers gold mineralization,whereas others hypothesize that the formation of lamprophyres increases the fertility of mantle sources and ore-forming fluids.K-feldspar veins,with ages between those of lamprophyres and gold deposits,appear in lamprophyres in Zhenyuan.Therefore,K-feldspar veins are ideal for investigating the relationship between lamprophyres and gold deposits.Phlogopite in K-feldspar veins has lower Mg#,Ni,and Cr contents and higher TiO2,Li,Ba,Sr,Sc,Zr,Nb,and Cs contents than phlogopite in lamprophyres.The in-situ Sr isotopic values of apatites(0.7063–0.7066)in K-feldspar veins are within the range for apatites(0.7064–0.7078)from lamprophyres.High large-ion lithophile element concentrations and low Nb and Ta concentrations in phlogopite from lamprophyres,in addition to high(87Sr/86Sr)i values of apatite(0.7064–0.7078),indicate that the magma parental to these phlogopite and apatite crystals is derived from an enriched mantle.Kfeldspar veins are genetically correlated with lamprophyres,whereas sulfide mineral assemblage and trace element compositions of pyrite in K-feldspar veins suggest that K-feldspar veins in lamprophyres are not directly related to gold mineralization of the Zhenyuan deposit.展开更多
This paper determined the fixed-ammonium (NH+-4) contents of lamprophyres in the Zhenyuan gold orefield, Yunnan Province, China. The results show that the NH+-4 contents of minettes in the orefield range from 120×...This paper determined the fixed-ammonium (NH+-4) contents of lamprophyres in the Zhenyuan gold orefield, Yunnan Province, China. The results show that the NH+-4 contents of minettes in the orefield range from 120×10-6 to 469×10-6 and those of kersantites from 74.3×10-6 to 136×10-6. These values are higher than those of other mantle-derived rocks (less than 50×10-6), but lower than those of carbonaceous wall rocks in the orefield (from 1200×10-6 to 1343×10-6). Combining with the Sr isotopic composition, this paper suggested that lamprophyres in the orefield with high NH+-4 contents relative to other mantle-derived rocks would not have resulted from the primary magma contaminated by crustal materials in the process of rising or in the magma chamber, but from mantle metasomatism.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41973045)Basic Science and Technology Research Funding of the CAGS(Grant No.JKYZD202312)+1 种基金the National Key Research and Development Project of China(Grant No.2022YFF0800903)National Natural Science Foundation of China(Grant Nos.41802113,42073053,42273073 and 42261144669).
文摘Lamprophyres typically appear in hydrothermal gold deposits.The relationship between lamprophyres and gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers gold mineralization,whereas others hypothesize that the formation of lamprophyres increases the fertility of mantle sources and ore-forming fluids.K-feldspar veins,with ages between those of lamprophyres and gold deposits,appear in lamprophyres in Zhenyuan.Therefore,K-feldspar veins are ideal for investigating the relationship between lamprophyres and gold deposits.Phlogopite in K-feldspar veins has lower Mg#,Ni,and Cr contents and higher TiO2,Li,Ba,Sr,Sc,Zr,Nb,and Cs contents than phlogopite in lamprophyres.The in-situ Sr isotopic values of apatites(0.7063–0.7066)in K-feldspar veins are within the range for apatites(0.7064–0.7078)from lamprophyres.High large-ion lithophile element concentrations and low Nb and Ta concentrations in phlogopite from lamprophyres,in addition to high(87Sr/86Sr)i values of apatite(0.7064–0.7078),indicate that the magma parental to these phlogopite and apatite crystals is derived from an enriched mantle.Kfeldspar veins are genetically correlated with lamprophyres,whereas sulfide mineral assemblage and trace element compositions of pyrite in K-feldspar veins suggest that K-feldspar veins in lamprophyres are not directly related to gold mineralization of the Zhenyuan deposit.
文摘This paper determined the fixed-ammonium (NH+-4) contents of lamprophyres in the Zhenyuan gold orefield, Yunnan Province, China. The results show that the NH+-4 contents of minettes in the orefield range from 120×10-6 to 469×10-6 and those of kersantites from 74.3×10-6 to 136×10-6. These values are higher than those of other mantle-derived rocks (less than 50×10-6), but lower than those of carbonaceous wall rocks in the orefield (from 1200×10-6 to 1343×10-6). Combining with the Sr isotopic composition, this paper suggested that lamprophyres in the orefield with high NH+-4 contents relative to other mantle-derived rocks would not have resulted from the primary magma contaminated by crustal materials in the process of rising or in the magma chamber, but from mantle metasomatism.
